Chiselling

Also called: paring, chopping

Chiselling is cutting or shaping wood with a chisel, a steel blade set in a handle, worked either by pushing it with the hand or driving it with blows from a mallet, depending on what the cut demands.

Paring and chopping

Chisels fall into two groups by how they cut: those used for paring and those used for chopping. Chopping severs the grain using sharp mallet blows and is best done with a short bench chisel, a general-purpose chisel sized for bench work; paring, by contrast, is guided entirely by hand pressure rather than a mallet and is kept for the finest work. A firmer chisel, a general all-round pattern, suits ordinary jobs either way, pushed by hand for paring or struck with a mallet for light mortising, the cutting of a slot to take a joint. Within these two families a chisel's exact job varies further, from chopping and mortising to shaving thin cuts or cleaning out waste left by other cuts. Chisels rank as a cabinetmaker's chief tools for paring work, and the corner paring chisel in particular handles light shaping and preparation on long flat surfaces, mostly working with the grain.

Bevel and choice of chisel

The angle ground on a chisel's cutting bevel, the sloped face behind the edge, reflects which of the two jobs it is meant for. A paring chisel carries a shallower bevel, typically 25 degrees and occasionally as low as 20, since it only ever meets hand pressure. A chopping chisel needs a steeper bevel, around 30 degrees, so that the impact of the mallet does not fracture the edge.

Cutting a mortise

Hand-cut mortising favours pushing with shoulder pressure over chopping wherever that is possible. Where chopping is used, a mortise is begun by working between the layout lines and stopping short of its two ends, with the cut usually started at the centre and deepened in stages moving toward each end; this sequence is then reversed to finish each end with a paring cut instead of a chopped one. Mortises are chopped somewhere solid on the bench, with the wood clamped across its thickness, to keep it from splitting. Where a mortise is being cut for hardware such as a lock, drilling with an oversize bit would weaken the door, so an undersize bit followed by extra paring to the line is preferred instead.

Working to a clean line

Before paring, a workpiece is fixed firmly in a vice, against a cutting board, or against a bench stop, and cut away up to the marked line with a sharp chisel held at a tilted angle. Cutting only partway through from one face before flipping the work and finishing from the other avoids a chipped underside where the chisel would otherwise break through. Paring upward from the bottom of a cut toward the surface tends to lift the wood fibres along the cut's edges. Scoring deeper gauge lines along the grain before cutting a housing, a slot cut across a board to house another piece, likewise helps stop the edge from breaking out. As a final cleanup step, end grain is pared down to the layout lines, and a shoulder can also be undercut slightly beyond where the initial chopping marks were made. A finely set chisel can pare away waste left in an internal corner, though well-maintained, correctly set tools rarely leave a corner needing this extra work. Before any of it, Moxon (1677) advised making several small cuts to prepare a piece, in his words, 'feveral cuttings, to cut it ftraight down, by little and little, till your work is made ready for the Paring Chiffcl.'

Specialised and improvised chisels

A shearcut bit shaves material rather than chopping it, broadly speaking, and stands apart from the ordinary paring-versus-chopping split. Some curved cuts need specialised tools: only long out-cannelled paring gouges, chisels ground with a curved, hollow bevel on the outside, and standard carving gouges are able to cut certain curve shapes, work usually left to pattern makers and carvers. Where no proper paring chisel is at hand, a serviceable one can be improvised by bolting a worn plane iron into a slotted wooden stick. Chopping mortises by hand was heavy work by any account: Sturt (1923) recalled that chopping timber for wheels was hard enough work to keep him warm through the winter, in his words, 'warm work, all this winter chopping of wheel-stuff was, and a good thing too.'